Chemistry( pure substances) Flashcards
What’s a pure substance
A single element or compound, not mixed with any other substance.
What do pure elements and compounds melt at ?
Specific temperatures
What can melting and boiling points be used for
To distinguish pure substances from mixtures
What’s a formulation
A mixture that has been designed as a useful product.
How are formulations made
By mixing the components In carefully measured quantities to ensure that the product has the required properties
Examples of formulations
- fuels
- cleaning agents
- paints
- medicines
- alloys
- fertilisers
- food
What can chromatography be used for ?
It can be used to separate mixtures and give information to help identify substances
What are the phases in chromatography
The • stationary phase
And the • mobile phase
Separation depends on the distribution of substances between the phases
What’s the main thing that happens in PAPER CHROMATOGRAPHY
A solvent moves through the paper carrying different compounds different distances. Depending on their attraction for the paper and the solvent
What’s the equation of the Rf value ( ratio of the distance moved by a compound - centre of the spot from origin- to the Distance moved by the solvent )
Distance moved by substance
Rf = ———————————————
Distance moved by solvent
What can the substance be in paper chromatography
Ink
What can the solvent be in paper chromatography ?
Water
How do u test for hydrogen ?
Hold a burning splint to a test tube to hear a pop ( squeaky pop test )
How do you test for oxygen ?
Put a glowing splint in a test tube of gas. If there’s oxygen it will re- light the splint
How do you test for carbon dioxide?
When carbon dioxide is shaken with calcium hydroxide ( lime water ) it turn a milky colour ( cloudy)
